Question: Solve for $x$ and $y$ using substitution. ${-2x+5y = -1}$ ${x = 4y-1}$
Explanation: Since $x$ has already been solved for, substitute $4y-1$ for $x$ in the first equation. ${-2}{(4y-1)}{+ 5y = -1}$ Simplify and solve for $y$ $-8y+2 + 5y = -1$ $-3y+2 = -1$ $-3y+2{-2} = -1{-2}$ $-3y = -3$ $\dfrac{-3y}{{-3}} = \dfrac{-3}{{-3}}$ ${y = 1}$ Now that you know ${y = 1}$ , plug it back into $\thinspace {x = 4y-1}\thinspace$ to find $x$ ${x = 4}{(1)}{ - 1}$ $x = 4 - 1$ ${x = 3}$ You can also plug ${y = 1}$ into $\thinspace {-2x+5y = -1}\thinspace$ and get the same answer for $x$ : ${-2x + 5}{(1)}{= -1}$ ${x = 3}$